Moulded ice creams have been produced for decades wherein a frozen aerated ice cream is filled in a mould the resulting product being then de-moulded. The problem with such technologies is that the resulting product sticks to the mould surface. Various solutions have been presented ranging from reheating the mould surface to using a film between the mould surface and the ice cream product.
More recently, it has been discovered that if the mould is at a sufficiently low temperature, typically below 60° C., preferably below 80° C., the ice cream product does not stick to the mould any longer. Such a phenomenon as for example been described in WO90/06693, EP582327, and EP 827,696. In these processes the mould is generally cooled with liquid nitrogen.
Whereas, the use of a cryogenically cooled moulds solved the problem of the adhesion of the ice cream to the mould, it creates another one. If the mould is filled through a nozzle which touches it (for example in order to fill a close cavity and to prevent the ice cream from flowing out of the cavity), the nozzle, through heat exchange with the cryogenically cooled mould, sees its temperature dropping up to the point where the ice cream freezes inside the nozzle and does not flow anymore out of the nozzle into the cavity. The problem becomes very significant when the mould temperature drops below −20° C. and extremely acute when the temperature drops below −40° C.
Trying to solve this problem, the applicant found that simply heating the nozzle does not work since, it creates a temperature gradient between the heating means and the mould. In this temperature gradient there is a zone which is at a temperature wherein the ice cream will adhere to the nozzle.
It has now been found that a careful design of the nozzle together with specific operating conditions allow for this problem to be solved.